A frequency inverter for driving a single motor is known, for example, from applicant's sales brochure "BELTRO-VERT Frequenzumrichter/Frequency Inverter 1.1 kW-2.2 kW."
Because of good controllability, frequency inverters can be used in machines in which several shafts are driven at differently variable rotational speeds. Because of the absence of suitable frequency inverters in the past, it has been common practice to use a single motor in these cases and drive the several shafts from the single motor via adjustable gear mechanisms. The frequency inverter described in applicant's brochure permits one motor and one controllable frequency inverter be coupled to each shaft.